Australian Dental Journal

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1 Australian Dental Journal The official journal of the Australian Dental Association SCIENTIFIC ARTICLE Australian Dental Journal 2010; 55: doi: /j x Relative oral health outcome trends between people inside and outside capital city areas of Australia LA Crocombe,* JF Stewart,* PD Barnard, GD Slade,à K Roberts-Thomson,* AJ Spencer* *Australian Research Centre for Population Oral Health, School of Dentistry, The University of Adelaide, South Australia. Australian Dental Association Inc., St Leonards, New South Wales. àdepartment of Dental Ecology, School of Dentistry, The University of North Carolina at Chapel Hill, North Carolina, USA. ABSTRACT Background: The aim of this study was to evaluate relative change over 17 years in clinical oral health outcomes inside and outside capital city areas of Australia. Methods: Using data from the National Oral Health Survey of Australia and the National Survey of Adult Oral Health , relative trends in clinical oral health outcomes inside and outside capital city areas were measured by age and gender standardized changes in the percentage of edentate people and dentate adults with less than 21 teeth, in mean numbers of decayed, missing and filled teeth, and mean DMFT index. Results: There were similar reductions inside and outside capital city areas in the percentage of edentate people (capital city 63.7%, outside capital city 60.7%) and dentate people with less than 21 teeth (52.5%, 50.1%), in the mean number of missing teeth (34.3%, 34.5%), filled teeth (0.0%, increase of 5.5%), and mean DMFT index (21.2%, 19.2%). The reduction in mean number of decayed teeth was greater in capital city areas (78.0%) than outside capital city areas (50.0%). Conclusions: Trends in four of the five clinical oral health outcomes demonstrated improvements in oral health that were of a similar magnitude inside and outside capital city areas of Australia. Keywords: Rural health inequalities, oral health, dental health surveys, epidemiology. Abbreviations and acronyms: CDs = collectors districts; DMFT = decayed, missing, and filled teeth; NOHSA = National Oral Health Survey of Australia; NSAOH = National Survey of Adult Oral Health. (Accepted for publication 10 November 2009.) INTRODUCTION The oral health status of Australian adults residing outside capital cities is poorer than that of people living in capital cities. 1 Using data from the National Survey of Adult Oral Health (NSAOH), 2 Roberts- Thomson and Do 3 reported that people residing outside capital cities were more likely to suffer complete tooth loss, to have an inadequate dentition (less than 21 teeth), and to have more missing teeth than capital city residents. They also suffered from a higher dental caries experience, with a higher percentage of people having untreated coronal dental caries and a higher mean DMFT (decayed, missing and filled teeth). Suggestions of why clinical oral health outcomes outside capital city areas are poorer than in capital city areas have been put forward. These include that water fluoridation is less common in areas outside capital cities than in capital city areas, a fact confirmed by the water fluoridation map of Australia. 4 It has also been noted that rurally-located people were more likely to have a lower socio-economic status 5 and that a marked socio-economic inequality in oral health exists in Australian adults. 6 An area of particular interest has been the fact that people from rural areas have poorer access to dental care than their urban counterparts, 1 and it has also been suggested that they have a different concept of health, 7,8 both of which influence health service utilization. An imbalance in availability of general health services has been noted between urban and rural locations in Australia, with rural areas characterized by fewer facilities and a shortage of health personnel. 9 Reducing inequalities in oral health was a major emphasis of Australia s National Oral Health Plan. 10 Monitoring of the changes in levels of population clinical oral disease may give some insight into oral disease aetiology and the reason for the differences in 280 ª 2010 Australian Dental Association

2 Urban and rural oral health outcome trends oral health inside and outside capital city areas. It is a critical part of the assessment of public health and important for the planning of oral health service provision. The information is essential for guiding current and future efforts to improve population oral health. The clinical oral health outcomes of Australians improved over the 17 years between and The percentage of people who had no natural teeth halved, whilst the mean number of teeth with dental decay more than halved (60%) and the percentage of people with fewer than 21 teeth reduced by a third. There was also a moderate net decrease (15%) in the mean number of DMFT. As the first step in investigating clinical oral health outcomes of people residing in and outside capital city areas, this study aimed to determine if the difference in clinical oral health outcomes between people who live inside and outside capital cities of Australia reduced in the 17-year period after The null hypothesis was that it did not. MATERIALS AND METHODS Clinical adult oral disease indicators inside and outside capital city areas were obtained from the only two national cross-sectional oral health surveys that have been held in Australia. Each survey collected similar information on clinical oral health outcomes of the adult population from different stratified samples of people. The changes over the 17-year period between the surveys in the clinical oral health outcome indicators inside and outside capital city areas of Australia were compared. The first survey was the National Oral Health Survey of Australia (NOHSA) conducted in The NOHSA was a cross-sectional study of a random sample of Australian residents aged 5+ years selected from the six states and the Australian Capital Territory. Northern Territory residents were not included due to lack of survey resources. Thirteen sampling strata were defined by capital city and non-capital city, a random sample of census collectors districts (CDs) was selected from each stratum, and within each CD a random sample of eight households was selected. Households were identified by consulting a map of each CD, selecting a starting grid point at random and then systematically selecting subsequent households along a pre-determined route using a pre-determined skip interval. Each sampled household was visited, and all people living in the household were invited to take part in the interview and examination. Details of examination protocol and survey participation have been described elsewhere. 12 For the current study, only people aged 15 years or older were used for the comparison. The second survey was the National Survey of Adult Oral Health (NSAOH) conducted in NSAOH used a clustered stratified random sampling design to select a representative sample of people aged 15 years or more. Survey participants were interviewed by telephone and those who had one or more natural teeth were asked to attend a nearby dental clinic where standardized oral epidemiological examinations were conducted by one of 30 dentist examiners trained in the survey methods. Full details of sampling, examination protocol and survey participation have been described elsewhere. 13 Capital city versus non-capital areas of Australia Postcodes were used to create two groups based on the Australian Bureau of Statistics postcode geographic classification: capital city ( metropolitan stratum) and remainder of state ( ex metropolitan stratum). The Australian Capital Territory was defined as a single metropolitan stratum. Data from the Northern Territory were omitted from the analyses of the NSAOH dataset to ensure that the two samples were comparable. Clinical oral health outcomes Clinical oral health outcomes for each group were defined by the percentage of edentate people, and in dentate adults by the percentage of people with less than 21 permanent teeth, the mean number of decayed permanent teeth, the mean number of missing permanent teeth, the mean number of filled permanent teeth, and the mean DMFT. The loss of all teeth is a fundamental indicator of dental impairment 3 and edentulous people report poorer subjective oral health than people who have natural teeth. 14 Having less than 21 permanent teeth was used as an indicator of an inadequate dentition. The literature reports that 20 natural teeth were sufficient for satisfactory chewing function 15 and diet and nutritional status. 16 On the other hand, adults with fewer than 21 teeth were more likely to suffer impaired oral health-related quality of life compared to adults with more teeth. 17 The DMFT was used to reflect a person s lifetime experience of dental caries. The number of decayed permanent teeth reflected the burden of untreated disease in dentate adults. As well as being a measure of a person s experience of dental caries, the number of filled permanent teeth indicated patterns of dental treatment and access to dental care. Data analysis The trends in clinical oral health outcome indicator levels between people residing inside and outside ª 2010 Australian Dental Association 281

3 LA Crocombe et al. Australian capital city areas were computed. Direct age and gender standardization was undertaken using the 2005 Estimated Resident Population as determined by the Australian Bureau of Statistics as the reference population. The seven age groups used for the age standardization were the 10-year intervals from age 15 to 74 years and 75+ years. Change inside or outside the capital city areas that exceeded the sampling error was identified when there was not an overlap between the 95% confidence intervals and the amount of difference provided the basis for describing the magnitude of any change. Relative change in the level of clinical oral disease was computed as the percentage change of the clinical oral health outcome indicator from to The difference in the relative change in the clinical oral health outcome indicators between inside and outside capital city areas of Australia was considered statistically significant if the 95% confidence intervals did not overlap. The 95% confidence intervals of the relative change in the clinical oral health outcome indicators were calculated as the square root of the sum of the squares of the separate 95% confidence intervals. SUDAAN (Research Triangle Institute, Research Triangle Park, NC, USA) was used to adjust for complex analytical design, to weight for sampling probability and non-response, and to undertake the direct age and gender standardization. RESULTS NOHSA was held in and people were interviewed, of whom (85.4%) had an oral examination. 12 NSAOH was held in , and of the people interviewed, 5505 (43.7%) were examined. 13 Comparison of the age and gender standardized figures indicated that, from to , the decrease in the percentage of people who were edentate was similar inside and outside capital city areas (Table 1). The proportion of adults outside the capital city areas who were edentate reduced between and by 60.7% (95% CI = ), and in capital city areas by 63.7% ( ). A similar reduction was found in the percentage of dentate adults with less than 21 teeth between the two surveys outside capital city areas (50.1%: ) and in capital city areas (52.5%: ). The mean number of decayed permanent teeth per dentate person decreased less outside capital city areas (50.0%: ) relative to in capital city areas (78.0%: , Table 2). The difference in the reduction was statistically significant as indicated by the fact that the 95% confidence intervals did not overlap. In there was not a statistically significant difference in mean number of decayed teeth between inside and outside capital city areas as reflected in the overlapping 95% confidence intervals (capital city: 1.4: , outside capital city: 1.6: ). However, in there was a statistically significant difference in mean number of decayed teeth between capital city and non-capital city areas of Australia (capital city: 0.5: , outside capital city: 0.8: ). The mean number of missing teeth decreased by a similar proportion inside and outside capital city areas (just over 34%). Dentate adults from outside capital city areas had a statistically significant greater mean Table 1. Inside and outside Australian capital city oral health outcomes in and age and gender standardized to the 2005 Australian Estimated Resident Population Oral health Capital city The rest of Australia % % % % Edentate 13.5 (12.4,14.7) 4.9 (4.4,5.4) 63.7% (54.8,72.6) 19.6 (18.1,21.2) 7.7 (7.1,8.4) 60.7% (52.5,69.9) Less than 21 teeth 25.5 (24.0,26.9) 12.1 (10.9,13.4) 52.5% (48.2,56.8) 33.7 (31.8,35.6) 16.8 (15.6,18.1) 50.1% (44.2,56.0) Table 2. Inside and outside Australian capital city dentate adult oral health outcomes in and age and gender standardized to the 2005 Australian Estimated Resident Population Caries experience Capital city The rest of Australia Decayed teeth 1.4 (1.3,1.5) 0.5 (0.4,0.6) 78.0% (68.0,88.0) 1.6 (1.4,1.7) 0.8 (0.7,1.0) 50.0% (36.3,63.7) Missing teeth due to pathology 7.0 (6.8,7.3) 4.6 (4.3,4.8) 34.3% (29.2,39.4) 8.4 (8.1,8.6) 5.5 (5.2,5.8) 34.5% (28.6,40.4) Filled teeth 8.0 (7.7,8.4) 8.0 (7.7,8.2) 0.0% ()5.3,5.3) 7.2 (6.9,7.6) 7.6 (7.2,8.0) )5.5% ()12.4,1.4) DMFT 16.5 (16.2,16.7) 13.0 (12.8,13.3) 21.2% (20.0,23.4) 17.2 (16.9,17.6) 13.9 (13.4,14.4) 19.2% (15.8,22.6) 282 ª 2010 Australian Dental Association

4 Urban and rural oral health outcome trends number of missing teeth than their capital city counterparts in both the and surveys. The mean number of filled teeth per dentate adult was similar in to in both inside and outside capital city areas. Dental caries experience as measured by the mean DMFT per dentate adult decreased by a similar amount outside capital city areas (19.2%: 15.8, 22.6) and in capital city areas (21.2%: 20.0, 23.4). DISCUSSION It has been previously reported that the level of clinical oral disease of Australians reduced between and However, this study has found that the relative difference in the clinical oral health outcomes between people residing inside and outside capital city areas did not reduce when measured by six clinical oral health outcome indicators. In fact, the relative difference in the mean number of decayed teeth between noncapital city and capital city areas increased between the two surveys. The study s shortcomings should be noted. NOHSA s count for missing teeth among people aged less than 45 years was deflated to a small degree compared to NSAOH because the former excluded teeth lost due to periodontitis. The DMFT index has inherent problems. For example, it suffers from its mixing of disease and treatment 18 and is based on the assumption that all filled teeth were carious prior to filling which may lead to an overestimation of the caries experience as expressed by the FT component of the DMFT. 19 However, whatever the shortcomings of any particular measure, all oral health outcome indicators showed that there was not a greater improvement in oral health for people living outside capital city areas compared to those living inside capital city areas, confirming a true trend. The comparison of participants of two crosssectional surveys may be open to criticism, but there was no other available way to compare the level of clinical oral disease of people at different points in time. NOHSA and NSAOH have been the only two national surveys held in Australia. The major strength of this study was the use of the only two national cross-sectional oral health surveys that have been held in Australia: large surveys that were representative of the Australian population at the time of each study. Measures of tooth loss have declined markedly over time in other OECD countries, such as the USA, 20 Germany 21 and the UK. 22 However, no other studies could be found that compared the relative changes over time in the levels of clinical oral health outcomes inside and outside capital city areas. As the rate of improvement in oral health outcomes outside capital city areas did not improve at a greater rate than in capital city areas, rural people continued to suffer a disproportionate share of the ill-effects of poor oral health. Research from as early as the 1980s has shown that oral health outcomes have a large societal impact. 23 The reduction in the mean number of decayed teeth per person being less outside capital city areas than in capital city areas suggested that Australians who reside outside the capital city areas continued to have poorer access to dental care. The continued greater number of missing teeth outside capital city areas than in capital city areas suggested late presentation for dental care. This is also an indicator of poorer access, but also indicates that busy rurally-based dentists may be more likely to extract teeth than capital city-based dentists. Access to dental care becomes more problematic the more remote a person s location. Teusner et al. 24 reported that the number of dentists per of the Australian population reduced as one travelled from major city areas (57.6), to inner regional areas (34.5), to outer regional areas (27.7) and to remote areas (18.1). The lower dentist numbers in regional areas has been reported to be reflected in the dental services received. For example, people living in non-capital city areas were less likely to have made a dental visit within the previous 12 months, and those who had visited were more likely to have had one or more teeth extracted and less likely to have received a professional clean and polish. 1 Australia faces a great challenge in reducing its inequalities in oral health outcomes. Further research is required into why people residing outside the capital cities of Australia continue to have poorer clinical oral health outcomes than their capital city counterparts. CONCLUSIONS Although clinical oral health outcomes have improved in most areas of Australia, it has been similar outside the capital city areas relative to within capital city areas. The gap in oral health outcomes remained at least as wide in as it was in with all six measures. In the case of the mean number of decayed permanent teeth, the divide was greater in than it was 17 years previously. The clinical oral health outcomes of people who reside outside the capital cities have not been catching up with that of people who reside within capital city areas. ACKNOWLEDGEMENTS The following organizations supported the National Oral Health Survey, Australia : National Health and Medical Research Council; Commonwealth ª 2010 Australian Dental Association 283

5 LA Crocombe et al. Department of Health; Australian Bureau of Statistics; state and territory health departments; and state branches of the Australian Dental Association combined to implement the survey. The following organizations supported the National Survey of Adult Oral Health : National Health and Medical Research Council, Project Grant No ; Australian Government Department of Health and Ageing, Population Health Division; Australian Institute of Health and Welfare; Colgate Oral Care; Australian Dental Association; and US Centers for Disease Control and Prevention. REFERENCES 1. Australian Institute of Health and Welfare. Geographic variation in oral health and use of dental services in the Australian population AIHW Dental Statistics and Research Unit Research Report No. 41. AIHW Cat. no. DEN 188. Adelaide: AIHW, Slade GD, Spencer AJ, Roberts-Thomson KF. Australia s dental generations. The National Survey of Adult Oral Health Canberra: Australian Institute of Health and Welfare, Roberts-Thomson K, Do L. Oral health status. In: Slade GD, Spencer AJ, Roberts-Thomson KF, eds. Australia s dental generations. The National Survey of Adult Oral Health Canberra: Australian Institute of Health and Welfare, 2007: Australian Research Centre for Population Oral Health. Water fluoridation map of Australia updated to URL: Accessed 27 July Australian Bureau of Statistics. A Picture of the Nation: the Statistician s Report on the 2006 Census, URL: Accessed 27 July Sanders AE, Slade GD, Turrell G, Spencer AJ, Marcenes W. The shape of the socioeconomic-oral health gradient: implications for theoretical explanations. Community Dent Oral Epidemiol 2006;34: Humphreys JS, Mathews-Cowey S, Weinand HC. Factors in accessibility of general practice in rural Australia. Med J Aust 1997;166: Coster G, Gribben B. Primary care models for delivering population-based health outcome. Wellington, New Zealand: National Health Committee, Humphreys JS. Social provision and service delivery: problems of equity, health, and health care in rural Australia. Geoforum 1988;19: National Advisory Committee on Oral Health. Healthy mouths, healthy lives: Australia s National Oral Health Plan Adelaide: Government of South Australia on behalf of the Australia s Health Minister s Conference, Slade GD, Sanders AE. Trends in oral health In: Slade GD, Spencer AJ, Roberts-Thomson KF, eds. Australia s dental generations. The National Survey of Adult Oral Health Canberra: Australian Institute of Health and Welfare, 2007: Barnard PD. National Oral Health Survey of Australia Canberra: Australian Government Publishing Service, Mejia GC, Slade GD, Spencer AJ. Participation in the survey. In: Slade GD, Spencer AJ, Roberts-Thomson KF, eds. Australia s dental generations. The National Survey of Adult Oral Health Canberra: Australian Institute of Health and Welfare, 2007: Slade GD, Spencer AJ. Social impact of oral conditions among older adults. Aust Dent J 2007;39: Elias AC, Sheiham A. The relationship between satisfaction with mouth and number and position of teeth. J Oral Rehabil 1998;25: Sheiham A, Steele JG, Marcenes W, Finch S, Walls AW. The relationship between oral health status and Body Mass Index among older people: a national survey of older people in Great Britain. Br Dent J 2002;192: McGrath C, Bedi R. Population-based norming of the UK oral health related quality of life measure (OHQoL-UK). Br Dent J 2002;193: Burt BA. How useful are cross-sectional data from surveys of dental caries? Community Dent Oral Epidemiol 1997;25: Spencer AJ. Skewed distributions new outcome measures. Community Dent Oral Epidemiol 1997;25: Dye BA, Tan S, Smith V, et al. Trends in oral health status: United States, and National Center for Health Statistics. Vital Health Stat 2007;11: Micheelis W, Schiffner U, eds. Fourth German Oral Health Study (DMS IV). Present results on the prevalence of oral diseases, risk groups and the degree of dental care in Germany Materialienreihe Volume Kelly MJ, Steele JG, Nuttall N, et al. Adult dental health survey: oral health in the United Kingdom in London: TSO, Spencer AJ, Lewis JM. The delivery of dental services: information, issues and directions. Community Health Studies 1988;12: Teusner DN, Chrisopoulos S, Brennan DS. Geographic distribution of the Australian dental labour force, AIHW Cat. no. DEN 168. Dental Statistics and Research Series No. 37. Canberra: Australian Institute of Health and Welfare, Address for correspondence: Dr Leonard Crocombe Australian Research Centre for Population Oral Health School of Dentistry The University of Adelaide Adelaide SA leonard.crocombe@adelaide.edu.au 284 ª 2010 Australian Dental Association